Canonical Domains allow you to have several 'domains' based off of your primary domain name. Canonical domains are also often referred to as vanity
domains. An example of a canonical domain would be sales.example.com where 'sales' is the canonical portion of the root domain example.com.

Canonical Domains can serve several purposes.

Canonical Domains can be used to increase your website's search engine ranking by choosing domains that include import keywords website. (i.e.
free.example.com)

They can easily give you a quick way to direct users to specific areas of your site via a short web address. (i.e. specials.example.com points to
www.example.com/sales/promos/specials)

Canonicals can be used to give your company a more professional appearance by creating separate 'departments'. (i.e. sales.example.com,
support.example.com, secure.example.com for Orders)